/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package com.csdig.db.core;

import java.beans.BeanInfo;
import java.beans.IntrospectionException;
import java.beans.Introspector;
import java.beans.PropertyDescriptor;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import java.sql.SQLException;
import java.sql.Timestamp;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

/**
 * <p>
 * <code>BeanProcessor</code> matches column names to bean property names and converts <code>ResultSet</code> columns into
 * objects for those bean properties. Subclasses should override the methods in the processing chain to customize behavior.
 * </p>
 * 
 * <p>
 * This class is thread-safe.
 * </p>
 * 
 * @see BasicRowProcessor
 * 
 * @since DbUtils 1.1
 */
public class BeanProcessor {

    private Log log = LogFactory.getLog(BeanProcessor.class);

    /**
     * Special array value used by <code>mapColumnsToProperties</code> that indicates there is no bean property that matches a
     * column from a <code>ResultSet</code>.
     */
    protected static final int PROPERTY_NOT_FOUND = -1;

    /**
     * Set a bean's primitive properties to these defaults when SQL NULL is returned. These are the same as the defaults that
     * ResultSet get* methods return in the event of a NULL column.
     */
    private static final Map<Class<?>, Object> primitiveDefaults = new HashMap<Class<?>, Object>();

    static {
        primitiveDefaults.put(Integer.TYPE, 0);
        primitiveDefaults.put(Short.TYPE, (Short) ((short) 0));
        primitiveDefaults.put(Byte.TYPE, (Byte) ((byte) 0));
        primitiveDefaults.put(Float.TYPE, (Float) (float) (0));
        primitiveDefaults.put(Double.TYPE, (Double) (double) (0));
        primitiveDefaults.put(Long.TYPE, (Long) (0L));
        primitiveDefaults.put(Boolean.TYPE, Boolean.FALSE);
        primitiveDefaults.put(Character.TYPE, '\u0000');
    }

    private ColumnFilter filter;

    /**
     * Constructor for BeanProcessor.
     */
    public BeanProcessor() {
        super();
    }

    public BeanProcessor(ColumnFilter fitler) {
        this.filter = fitler;
    }

    /**
     * Convert a <code>ResultSet</code> row into a JavaBean. This implementation uses reflection and <code>BeanInfo</code>
     * classes to match column names to bean property names. Properties are matched to columns based on several factors: <br/>
     * <ol>
     * <li> The class has a writable property with the same name as a column. The name comparison is case insensitive. </li>
     * 
     * <li> The column type can be converted to the property's set method parameter type with a ResultSet.get* method. If the
     * conversion fails (ie. the property was an int and the column was a Timestamp) an SQLException is thrown. </li>
     * </ol>
     * 
     * <p>
     * Primitive bean properties are set to their defaults when SQL NULL is returned from the <code>ResultSet</code>. Numeric
     * fields are set to 0 and booleans are set to false. Object bean properties are set to <code>null</code> when SQL NULL is
     * returned. This is the same behavior as the <code>ResultSet</code> get* methods.
     * </p>
     * 
     * @param <T>
     *            The type of bean to create
     * @param rs
     *            ResultSet that supplies the bean data
     * @param type
     *            Class from which to create the bean instance
     * @throws SQLException
     *             if a database access error occurs
     * @return the newly created bean
     */
    public <T> T toBean(ResultSet rs, Class<T> type) throws SQLException {

        PropertyDescriptor[] props = this.propertyDescriptors(type);

        ResultSetMetaData rsmd = rs.getMetaData();
        int[] columnToProperty = this.mapColumnsToProperties(rsmd, props);

        return this.createBean(rs, type, props, columnToProperty);
    }

    /**
     * Convert a <code>ResultSet</code> into a <code>List</code> of JavaBeans. This implementation uses reflection and
     * <code>BeanInfo</code> classes to match column names to bean property names. Properties are matched to columns based on
     * several factors: <br/>
     * <ol>
     * <li> The class has a writable property with the same name as a column. The name comparison is case insensitive. </li>
     * 
     * <li> The column type can be converted to the property's set method parameter type with a ResultSet.get* method. If the
     * conversion fails (ie. the property was an int and the column was a Timestamp) an SQLException is thrown. </li>
     * </ol>
     * 
     * <p>
     * Primitive bean properties are set to their defaults when SQL NULL is returned from the <code>ResultSet</code>. Numeric
     * fields are set to 0 and booleans are set to false. Object bean properties are set to <code>null</code> when SQL NULL is
     * returned. This is the same behavior as the <code>ResultSet</code> get* methods.
     * </p>
     * 
     * @param <T>
     *            The type of bean to create
     * @param rs
     *            ResultSet that supplies the bean data
     * @param type
     *            Class from which to create the bean instance
     * @throws SQLException
     *             if a database access error occurs
     * @return the newly created List of beans
     */
    public <T> List<T> toBeanList(ResultSet rs, Class<T> type) throws SQLException {
        List<T> results = new ArrayList<T>();

        if (!rs.next()) {
            return results;
        }

        PropertyDescriptor[] props = this.propertyDescriptors(type);
        ResultSetMetaData rsmd = rs.getMetaData();
        int[] columnToProperty = this.mapColumnsToProperties(rsmd, props);

        do {
            results.add(this.createBean(rs, type, props, columnToProperty));
        } while (rs.next());

        return results;
    }

    /**
     * Creates a new object and initializes its fields from the ResultSet.
     * 
     * @param <T>
     *            The type of bean to create
     * @param rs
     *            The result set.
     * @param type
     *            The bean type (the return type of the object).
     * @param props
     *            The property descriptors.
     * @param columnToProperty
     *            The column indices in the result set.
     * @return An initialized object.
     * @throws SQLException
     *             if a database error occurs.
     */
    private <T> T createBean(ResultSet rs, Class<T> type, PropertyDescriptor[] props, int[] columnToProperty)
            throws SQLException {

        T bean = this.newInstance(type);

        for (int i = 1; i < columnToProperty.length; i++) {

            if (columnToProperty[i] == PROPERTY_NOT_FOUND) {
                continue;
            }

            PropertyDescriptor prop = props[columnToProperty[i]];
            Class<?> propType = prop.getPropertyType();

            Object value = this.processColumn(rs, i, propType);
            
            if(this.filter!=null){
                value = filter.doFilter(prop.getDisplayName(), value);
            }

            if (propType != null && value == null && propType.isPrimitive()) {
                value = primitiveDefaults.get(propType);
            }

            this.callSetter(bean, prop, value);
        }

        return bean;
    }

    /**
     * Calls the setter method on the target object for the given property. If no setter method exists for the property, this
     * method does nothing.
     * 
     * @param target
     *            The object to set the property on.
     * @param prop
     *            The property to set.
     * @param value
     *            The value to pass into the setter.
     * @throws SQLException
     *             if an error occurs setting the property.
     */
    private void callSetter(Object target, PropertyDescriptor prop, Object value) throws SQLException {

        Method setter = prop.getWriteMethod();

        if (setter == null) {
            return;
        }

        Class<?>[] params = setter.getParameterTypes();
        try {
            // convert types for some popular ones
            if (value != null) {
                if (value instanceof java.util.Date) {
                    if (params[0].getName().equals("java.sql.Date")) {
                        value = new java.sql.Date(((java.util.Date) value).getTime());
                    } else if (params[0].getName().equals("java.sql.Time")) {
                        value = new java.sql.Time(((java.util.Date) value).getTime());
                    } else if (params[0].getName().equals("java.sql.Timestamp")) {
                        value = new java.sql.Timestamp(((java.util.Date) value).getTime());
                    }
                }
            }

            // Don't call setter if the value object isn't the right type
            if (this.isCompatibleType(value, params[0])) {
                setter.invoke(target, new Object[] { value });
            } else {
                throw new SQLException("Cannot set " + prop.getName() + ": incompatible types.");
            }

        } catch (IllegalArgumentException e) {
            throw new SQLException("Cannot set " + prop.getName() + ": " + e.getMessage());

        } catch (IllegalAccessException e) {
            log.error("Cannot set " + prop.getName() + ": " + e.getMessage());
            throw new SQLException("Cannot set " + prop.getName() + ": " + e.getMessage());

        } catch (InvocationTargetException e) {
            throw new SQLException("Cannot set " + prop.getName() + ": " + e.getMessage());
        }
    }

    /**
     * ResultSet.getObject() returns an Integer object for an INT column. The setter method for the property might take an Integer
     * or a primitive int. This method returns true if the value can be successfully passed into the setter method. Remember,
     * Method.invoke() handles the unwrapping of Integer into an int.
     * 
     * @param value
     *            The value to be passed into the setter method.
     * @param type
     *            The setter's parameter type.
     * @return boolean True if the value is compatible.
     */
    private boolean isCompatibleType(Object value, Class<?> type) {
        // Do object check first, then primitives
        if (value == null || type.isInstance(value)) {
            return true;

        } else if (type.equals(Integer.TYPE) && Integer.class.isInstance(value)) {
            return true;

        } else if (type.equals(Long.TYPE) && Long.class.isInstance(value)) {
            return true;

        } else if (type.equals(Double.TYPE) && Double.class.isInstance(value)) {
            return true;

        } else if (type.equals(Float.TYPE) && Float.class.isInstance(value)) {
            return true;

        } else if (type.equals(Short.TYPE) && Short.class.isInstance(value)) {
            return true;

        } else if (type.equals(Byte.TYPE) && Byte.class.isInstance(value)) {
            return true;

        } else if (type.equals(Character.TYPE) && Character.class.isInstance(value)) {
            return true;

        } else if (type.equals(Boolean.TYPE) && Boolean.class.isInstance(value)) {
            return true;

        } else {
            return false;
        }

    }

    /**
     * Factory method that returns a new instance of the given Class. This is called at the start of the bean creation process and
     * may be overridden to provide custom behavior like returning a cached bean instance.
     * 
     * @param <T>
     *            The type of object to create
     * @param c
     *            The Class to create an object from.
     * @return A newly created object of the Class.
     * @throws SQLException
     *             if creation failed.
     */
    protected <T> T newInstance(Class<T> c) throws SQLException {
        try {
            return c.newInstance();

        } catch (InstantiationException e) {
            throw new SQLException("Cannot create " + c.getName() + ": " + e.getMessage());

        } catch (IllegalAccessException e) {
            throw new SQLException("Cannot create " + c.getName() + ": " + e.getMessage());
        }
    }

    /**
     * Returns a PropertyDescriptor[] for the given Class.
     * 
     * @param c
     *            The Class to retrieve PropertyDescriptors for.
     * @return A PropertyDescriptor[] describing the Class.
     * @throws SQLException
     *             if introspection failed.
     */
    private PropertyDescriptor[] propertyDescriptors(Class<?> c) throws SQLException {
        // Introspector caches BeanInfo classes for better performance
        BeanInfo beanInfo = null;
        try {
            beanInfo = Introspector.getBeanInfo(c);

        } catch (IntrospectionException e) {
            throw new SQLException("Bean introspection failed: " + e.getMessage());
        }

        return beanInfo.getPropertyDescriptors();
    }

    /**
     * The positions in the returned array represent column numbers. The values stored at each position represent the index in the
     * <code>PropertyDescriptor[]</code> for the bean property that matches the column name. If no bean property was found for a
     * column, the position is set to <code>PROPERTY_NOT_FOUND</code>.
     * 
     * @param rsmd
     *            The <code>ResultSetMetaData</code> containing column information.
     * 
     * @param props
     *            The bean property descriptors.
     * 
     * @throws SQLException
     *             if a database access error occurs
     * 
     * @return An int[] with column index to property index mappings. The 0th element is meaningless because JDBC column indexing
     *         starts at 1.
     */
    protected int[] mapColumnsToProperties(ResultSetMetaData rsmd, PropertyDescriptor[] props) throws SQLException {

        int cols = rsmd.getColumnCount();
        int columnToProperty[] = new int[cols + 1];
        Arrays.fill(columnToProperty, PROPERTY_NOT_FOUND);

        for (int col = 1; col <= cols; col++) {
            String columnName = rsmd.getColumnLabel(col);
            if (null == columnName || 0 == columnName.length()) {
                columnName = rsmd.getColumnName(col);
            }
            for (int i = 0; i < props.length; i++) {
                String caseName = ColumnNameHelper.castColumnToClass(columnName);
                if (caseName != null && caseName.equalsIgnoreCase(props[i].getName())) {
                    columnToProperty[col] = i;
                    break;
                }
            }
        }

        return columnToProperty;
    }

    /**
     * Convert a <code>ResultSet</code> column into an object. Simple implementations could just call
     * <code>rs.getObject(index)</code> while more complex implementations could perform type manipulation to match the column's
     * type to the bean property type.
     * 
     * <p>
     * This implementation calls the appropriate <code>ResultSet</code> getter method for the given property type to perform the
     * type conversion. If the property type doesn't match one of the supported <code>ResultSet</code> types,
     * <code>getObject</code> is called.
     * </p>
     * 
     * @param rs
     *            The <code>ResultSet</code> currently being processed. It is positioned on a valid row before being passed into
     *            this method.
     * 
     * @param index
     *            The current column index being processed.
     * 
     * @param propType
     *            The bean property type that this column needs to be converted into.
     * 
     * @throws SQLException
     *             if a database access error occurs
     * 
     * @return The object from the <code>ResultSet</code> at the given column index after optional type processing or
     *         <code>null</code> if the column value was SQL NULL.
     */
    protected Object processColumn(ResultSet rs, int index, Class<?> propType) throws SQLException {

        if (!propType.isPrimitive() && rs.getObject(index) == null) {
            return null;
        }

        if (!propType.isPrimitive() && rs.getObject(index) == null) {
            return null;
        }

        if (propType.equals(String.class)) {
            return rs.getString(index);

        } else if (propType.equals(Integer.TYPE) || propType.equals(Integer.class)) {
            return (rs.getInt(index));

        } else if (propType.equals(Boolean.TYPE) || propType.equals(Boolean.class)) {
            return (rs.getBoolean(index));

        } else if (propType.equals(Long.TYPE) || propType.equals(Long.class)) {
            return (rs.getLong(index));

        } else if (propType.equals(Double.TYPE) || propType.equals(Double.class)) {
            return (rs.getDouble(index));

        } else if (propType.equals(Float.TYPE) || propType.equals(Float.class)) {
            return (rs.getFloat(index));

        } else if (propType.equals(Short.TYPE) || propType.equals(Short.class)) {
            return (rs.getShort(index));

        } else if (propType.equals(Byte.TYPE) || propType.equals(Byte.class)) {
            return (rs.getByte(index));

        } else if (propType.equals(Timestamp.class)) {
            return rs.getTimestamp(index);

        } else {
            return rs.getObject(index);
        }

    }

}
